Drop permissions to MEDIUM (APP level).
Drop permissions to MEDIUM (APP level).

Drop permissions as soon as initialization
is complete.  APP code is expected to run
at MEDIUM permission level.

BRANCH=none
BUG=chrome-os-partner:43025
TEST=serial shell starts up
Change-Id: I181d55ca96eb5998ad49856af9f82afb67b03024
Signed-off-by: nagendra modadugu <5dc366ddbf8fb5981f46478e8436ef712a08b71b@google.com>
Reviewed-on: https://chromium-review.googlesource.com/309919
Reviewed-by: Vadim Bendebury <5515d6d2d0829cbe0dd0dcf2094aaded06d58514@google.com>
Reviewed-by: Bill Richardson <129945214b1d548d8e49b6c29c43094f8c78057f@chromium.org>
Tested-by: Bill Richardson <129945214b1d548d8e49b6c29c43094f8c78057f@chromium.org>

akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec